The present invention relates to a high intensity electromagnetic radiation pulsed lamp and the like.
Pulsed lamps known in the art as flash lamps are important in a wide variety of commercial, military, industrial, academic, medical and environmental applications, including treatment of contaminated water and industrial effluent, laser excitation, paint stripping, curing, photography, decontamination, strobes, beacons, and the like. In commercially available flashlamps, electrical energy provided by a capacitor bank is deposited into a gas disposed between two electrodes enclosed in a transparent envelope, creating an electrical discharge. The electrical discharge produces a plasma that is a source of radiant energy, which ranges from the infrared to the ultraviolet regions of the electromagnetic spectrum. The flashlamp is repetitively pulsed to provide throughput for commercial applications.
Flashlamp geometries are, however, constrained by practical envelope shape considerations. For example, electrical initiation of the discharge favors small envelope diameters.
Also, the optical spectrum of most flashlamps has been limited by the choice of the discharge gas and the electrical power delivery system to the flashlamp.
High intensity UV light from flashlamps is also limited because of the close proximity of the plasma to the envelope material, which causes a reversible time dependent increase in absorption of UV light.
For high power applications, flashlamps are typically cooled by gas or liquid flow over the outside of the envelope. Moreover, flashlamps are typically initiated by a trigger on the outside of the envelope.
The Surface Discharge (SD) lamp is a pulsed lamp that is known in the art but has seen little commercialization. The SD lamp has many of the same generic characteristics of flashlamps but circumvents many of the limitations. In an SD lamp the electrical energy is discharged along the surface of a dielectric so that the light emitting plasma takes on the shape of the underlying dielectric. This has lead to SD lamps with envelopes having large areas and several geometries. Linear, rectangular, annular and cylindrical SD lamps are known in the art.
Many SD lamps are initiated by capacitive coupling from the initiating electrode to a conductor placed in contact with the dielectric. Because of the capacitive coupling, the threshold for plasma breakdown of an SD lamp occurs at a low voltage compared to flashlamps. Furthermore, other SD lamps are known in the art in which a conductor in contact with the dielectric provides a channel for coolant flow and also serves as an electrical conductor.
Some SD lamps known in the art are placed in series and/or employ intermediate electrodes to increase the discharge length. However, the length is limited by the voltage of the electrical driver.
Repetition rates of SD lamps can be faster than flashlamps because the plasma decay time is faster in the presence of the dielectric. Nevertheless, repetition rates have been limited to about 1 Khz.